Welding gun cooling structure and electrode tip retainer

ABSTRACT

A welding gun and cable apparatus utilizing quick connect and disconnect couplings to provide electrical current and shielding gas to a welding gun as well as a welding electrode if desired. The welding gun includes an elongate body having a gas passage and a passage formed between the body and an outer covering through which air flows by connection to cool the body. Additionally the gas passage may also contain a liner with radially sprung fingers at one end to outwardly bias against a welding tip to retain the welding tip in a nozzle portion.

United States Patent [191 dal Molin WELDING GUN COOLING STRUCTURE ANDELECTRODE TIP RETAINER Guido A. dal Molin, Westlake, Ohio [73] Assignee:Co-Ordinated Industries, Inc.,

Aliquippa, Pa. 1

[22] Filed: July 14, 1971 [21] Appl. No.: 162,678

Related US. Application Data 60] Division of Ser. No. 10,389, Feb. 11,1970, Pat. No. 3,610,875, which is a continuation-in-part of Ser. No.672,794, Oct. 4, 1967, Pat. No. 3,544,758.

[75] Inventor:

[52] US. Cl. 219/130, 219/74, 219/136 [51] Int. Cl B23k 9/00 [58] Fieldof Search 219/136, 130, 74,

[56] References Cited UNITED STATES PATENTS 7/1971 Ogden 219/136 X3/1969 Henriksen et a1 219/136 X [4 Jan. 1, 1974 Kester 219/136 X3,253,116 5/1966 Kensrue.... 219/130 3,541,298 11/1970 Carkhuff...219/130 2,347,646 I 5/1944 Smith 219/136 3,469,070 9/1969 Bernard et a1..219/130 I 3,155,811 11/1964 Adamson et a1 Primary ExaminerR. F.Staubly Assistant ExaminerGeorge A. Montanye AttorneyBosworth, Sessions,Herrstrom-& Cain 5 7 ABSTRACT A welding gun and cable apparatusutilizing quick 1 connect and disconnect couplings to provide electricalcurrent and shielding gas to a welding gun as well as a weldingelectrode if desired. The welding gun includes an elongate body having agaspassage and a passage formed between the body. and an outer coveringthrough which air flows by connection to cool the body. Additionally thegas passage may also contain a liner with radially sprung fingers at oneend to outwardly bias against a welding tip to retain the welding tip ina nozzle portion.

7 Claims, 12 Drawing Figures WELDING GUN COOLING STRUCTURE AND ELECTRODETIP RETAINER CROSS REFERENCE'TO RELATED APPLICATIONS This application isa division of application Ser. No. 10,389 filed Feb. 11, 1970 now US.Pat. No. 3,610,875 dated Oct. 5, 1971, which is a continuationin-part ofapplication Ser. No. 672,794, filed Oct. 4, 1967, now US. Pat. No.3,544,758 dated Dec. 1, 1970.

BACKGROUND OF THE INVENTION This invention relatesto a cable apparatusfor conducting gas and electricity, and welding wire if desired; andmore particularly to such apparatus comprising a flexible cable adaptedto be readily and quickly con nected to and disconnected fromconnectible means such as a welding gun, or such as means for feedinginto the cable gas, electrical current and welding wire if desired. o

For convenience, the invention will be described with reference togas-shielded consumable electric arc welding, in which use it providesparticular advantages, although features of it may be advantageouslyused in cutting apparatus as well as other types of apparatus embodyingflexible cables for conducting electrical current and gas.

In such welding, there is fedinto a welding zone in which the weldingoccurs consumable welding wire that acts as an electrode and isconnected to one side of an electrical welding circuit the other side ofwhich is connected to the work to be welded. It is common practice insuch welding to surround the welding zone with a shielding gas toprevent extraction from the ambient air of contaminants such as oxygenor nitrogen that have deleterious effect on the metal being welded. Theshielding gas may be an inert gas which is helium or argon andpreferably is continuously supplied to form a shield or curtain aroundthe tip of the welding wire in the welding zone. r

The apparatus heretofore widely used for such welding has embodied acable through which the welding wire passes and which conducts electriccurrent from the current supply to the welding zone. However, in suchapparatus the shieldinggas has usually been supplied by a separate hose,usually clipped to such cable and connected to one end to the source ofgas and the other end to the welding gun. This hose, being separate fromthe cable, often tends to become entangled with objects in the vicinityof the welding zone and also is often in the way of the operator andimpairs his welding efficiency.

Such prior widely used welding cable also usually has a connectorportion at one end, to which the welding head or gun is attached, and adifferent type connector portion at the other end to which is attachedmeans for feeding the electrode wire to the cable. Usually, the end ofthe cable near the welding tends to wear most since it is handled by theoperator and in service is often dragged over the flooror other support.Consequently, when the cable becomes excessively worn on one end, theusual practice is to cut off the one end of the cable and reattach thesevered connector portion to the new unworn end. This is a laborious andtime consuming process and inevitably eventually results in a cable thatis undesirably short.

Furthermore, in such prior apparatus, the welding gun is usuallyconnected to the end of the cable by cumbersome means that requiresconsiderable time to make a gun change, as is often necessary in weldingactivities. In such usual prior cable apparatus, moreover, there is noprovision permitting rotation of the gun relative to the cable, sowelding efficiency is reduced because of difficulty in manipulating thegun when it is immovably attached to the relatively stiff cable.

Structures of cables and guns have been proposed to overcome some ofsuch difficulties. In some cases, proposals have been made to permit agun to be rotatably mounted relative to the cable, but in general such agun is not readily removable from the cable, as is often desired inproduction welding. Furthermore, there are no provisions permitting thegun to be readily locked or secured in a position to which it is rotatedsince friction is relied upon as the only means to position the gun.

Prior gun constructions have also been efficient in construction andmounting of the welding tip to which the welding wire passes. In priorconstructions in general it has been very difficult to remove andreplace the welding tip, which usually in time deteriorates due to heat,or which must be replaced to handle a different size of welding wire.Furthermore, in prior constructions it has usually been difficult toremove and replace the gas-confining shield, usually taking the form ofa sleeve, around the welding tip. Removal is necessary to permit accessto the welding tip so it can be replaced, and to permit replacement ofthe shield if it deteriorates from heat. 5

Furthermore, prior constructions have often been deficient in that thewelding wire entering the cable has had unremoved dirt orothercontaminant particles on it which can cause clogging or abrasion ofthe passages through the cable or the welding tip and hence impairproper welding.

SUMMARY OF THE INVENTION An object of the present invention is theprovision of apparatus that eliminates as many of the abovedisadvantages as desired. Another object is the provision of suchapparatus in which shielding gas, electrical current, and if desiredwelding electrode wire, are all passed through the same cable. A furtherobject of the invention is the provision of a cable having at at leastone end a connector portion making it possible quickly and easily toconnect and disconnect the gun, or other connectible means such as afeeder, to and from the cable, while providing an electricallyconductive and gas tight joint between the cable and connectible means.Another object is the provision of such apparatus in which the gun orother connectible means can be rotated relative to the cable, and can bereadily Secured in any one of a number of rotative positions relative tothe cable. Another object is the provision of such apparatus in whichthe cable has identical connector portions at both ends so that bothends of the cable can be disconnected from the welding gun and from thefeeder and the ends of the cable can be interchanged to equalize wear. Afurther object of the invention is to provide improved gun apparatus.Another is to provide improved feeder means. Another object is theprovision of such apparatuses which are durable and can be man-.ufactured at reasonable costs.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and featuresof the invention will become apparent from the following description ofa preferred embodiment in connection with the accompanying drawings inwhich:

FIG. 1 is an exterior view to a small scale of the apparatus embodyingthe invention, showing a welding cable of the invention connected at oneend to a welding gun and the other end to feeder means for feedingwelding wire, shielding gas, and electrical current to the cable;

FIG. 2 is a longitudinal sectional elevation to an enlarged scale, ofthe gun end of the cable, showing the construction of one of theconnector portions, and also the internal construction of a welding gunembodying the invention connected to such connector portion;

FIG. 3 is a section'along lines 3-3 of FIGS. 1 and 4, and to the samescale as FIG. 2, of a feeder for feeding the gas, electrode wire, andelectrical current to the cable;

FIG. 4 is a section along line 4-4 of FIG. 3;

FIG. 5 is a section along line 5--5 of FIG. 2;

FIG. 6 is a section along line 6-6 of FIG. 2;

FIG. 7 is a section along line 77 of FIG. 2;

FIG. 8 is a section along line 8-8 of FIG. 2;

FIG. 9 is a side elevation of the gun, shown as disconnected from an endmember of the cable and also shown as having the welding tip and shielddisassembled from the gun;

7 FIG. 10 is a longitudinal sectional elevation of the welding tip;

FIG. 11 is a longitudinal sectional elevation of the shield; and FIG. 12is a sectional elevation of an end member of the cable, shown asdisassembled from the cable structure as a whole.

DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus as shown in FIG. 1comprises a cable 1 having a central portion 2, welding gun 3 connectedto one end of the cable, and feeder means 4 at the other end of thecable. Electrode wire E is fed through the cable by feeder portion 4 andis discharged from the gun 3. .Shielding gas is supplied by hose 5 tofeeder means 4 and is also discharged through the gun 3. Feeder means 4is connected by wire 6 to one side of a known electrical energy supplycircuit, while the work W is connected by wire 7 to the other side ofthe circuit. Wires 8 and 9 which pass through a sheath ll surroundingthe central portion 2 of the cable, are connected through switch 12 tosuitable known means to control the flow of electricity through thecable and to wire E, and to control the travel of wire E.

As shown in FIGS. 2, 4 and 5, the cable comprises a flexible, resilient,circularsectioned inner tubular sheath 13 formed of material that ispreferably nonmagnetic and electrically nonconductive, such as naturalor synthetic rubber, plastic material, or other suitable polymericmaterial. This sheath, preferably seals against passage of gas ormoisture.

A flexible electrically conductive circular-sectioned sheath l4surrounds and supports the inner sheath. Sheath 14 is formed of one ormore layers of electrically conductive material, such as copper strand15, that acts as the electrical conductor; in this embodiment sheath 14is one layer of strand 15 that is wound in a helix of steep pitch, asshown externally in FIG. 2, each strand being formed of a large numberof spirally wound wires of small diameter for increased flexibility.

An outer circular-sectioned sheath 16 of flexible, resilient,electrically nonconductive, nonmagnetic material, such as natural orsynthetic rubber, plastic material or other suitable material, surroundsconductive sheath 14, preferably being molded in place over sheath 14 toform a gas and moisture-tight cover.

If desired, as shown in the illustrated embodiment, there may be anotherexternal sheath 17 that is loosely slipped over the surface of sheath l6and is shaped to carry internally the conductors 8 and 9 adjacent sheath16.

A hollow flexible liner 18 having a passage opening 19 through whichelectrode wire E passes extends through the inner sheath 15.'In thisembodiment the liner is formed of a flexible, nonmagnetic, nonconductivewear-resistant synthetic resin material such as nylon, although it couldbe formed of nonmagnetic metal such as stainless steel. This liner,which is removable, is surrounded by and radially spaced at 20 from theinside wall of sheath 13. As shown in FIG. 5, the interior 19 of liner18 provides passage for the electrode wire E and a small amount of gas,while the space 20 between the liner and the inner sheath provides anannular space of substantial volume for passage of gas. Sheath 14conducts the necessary electrical current.

At each end of the cable, there is a connector portion 21 that supportsthe liner 18, and is connected to the inner sheath 13, conductive sheath14, and external sheath 16. Each connector portion comprises a member 22formed of metal of good electrical conductivity, such as aluminum,brass, or copper; it includes a body portion 23 at the extreme end ofthe cable structure, an intermediate portion 24 of reduced diameter andan end portion 25 of smaller diameter extending toward the cable andseparated from portion 24 by shoulder 26. Portion 24 is externallythreaded at 27 while portion 25 has an externally threaded tapered endportion 28 that provide external transverse gripping projections.

A nut or sleeve member 29 formed of electrically conductive metal isinternally threaded at its front end portion 30 to engage threads 27 ofmember 22. The remaining inner surface of member 29 is shaped as shown,with an inner ridge 31 of smallest diameter toward the rear of member 29and followed by a cylindrical internal wall 33 of largest diameterterminating in shoulders 34; the inner surface is completed by a portion35 having internal transverse gripping projections such as threadsdefining a smaller diameter than the cylindrical portion, and anoutwardly tapered portion 36.

The external surface of portion 23 of member 22, and the externalsurface of nut member 29 preferably are of hexagonal or other suitableshape providing flat wrench-engagable surfaces. In manufacture, thecable assembly made up of inner sheath l3, conductive sheath l4, andexternal sheath 16 has each end preliminarily formed so that sheaths l3and 14 are of the same length, while sheath 16 is cut back a suitabledistance so its end will terminate in the recess defined by wall 33 ofmember 29 (FIG. 2).

A member 29 is then slid over the external sheath at each end of thecable assembly, with its thread portion 30 facing the free end of theassembly. At each end, the cable assembly of sheaths 13, 14, and 16 isthen forced over the projecting portion of a connector member 22 untilthe end of the assembly abuts shoulder 26, after which portion of member29 is threaded onto threaded portion 27 of member 22. This causes member29 in cooperation with member 22 firmly to clamp outer sheath 16 withits exterior surface engaging internal gripping threads and its endextending into the cylindrical annular recess defined by wall 33 ofmember 29, where it is locked between shoulders 34; to force the innersurface of inner sheath 13 to engage the gripping threads 28 on member22; and to clamp the end portion of conductive sheath 14 between innerridge 31 of member 29 and the external surface of inner sheath 13 onportion 25, and also between the portion of outer sheath 16 gripped byrecess 33 and threaded portion 35 of member 29 and the portion of innersheath 13 that is gripped by portion 25 of member 22 and particularlythreaded portion 28. Moreover, the portion 35 of member 29 havinginternal gripping threads engaging sheath l6 overlaps the externallythreaded portion 27 of member 22 having external gripping taperedthreads engaging sheath 13, to provide added wedging and clamping actionthat 'adds great resistance to longitudinal movement of the cableassembly out from connector portion 21.

The ends of the cable assembly, therefore, are firmly anchored in eachconnector portion 21; moreover, there are large metal-to-metal areasproviding conductivity for large electrical currents from the externalsurface of the conductive sheath 14 to the inner surface of nut member28, and from the nut member through the threaded joints 27, 30 to member22.

Furthermore, the construction is such that the cable assembly can bereadily disconnected from, or reconnected to, each of the connectormembers 22.

Each connector member 22 at its free end has a socket recess 38 that iscircular in cross section about an axis A substantially coincident withthe axis of the cable assembly. The recess decreases in diameter fromthe free end of member 22 toward the bottom of the recess, the innersurface 39 of the recess being preferably, as shown, frustoconical inshape. The depth of the recess is substantial, being preferably at leastas great as,and preferably at least one and a half times, its maximumdiameter. An axial opening 49 extends from the recess 38 to the innerend of member 23; it has internal spaced longitudinal ribs 40a (FIG. 12)that locate the liner 18 transversely while permitting gas to flowoutside the liner.

Each member 22 also has, near its free end, a threaded opening 41adapted to receive a setscrew 42 having its axis lying in a planecontaining axis A of recess 38. Another threaded opening 43 having itsaxis in a plane containing axis A and opening into passage 40 also ispreferably provided. In member 22 shown in FIG. 2, to which gun 3 isconnected, this opening is closed gas-tight by screwplug 44.

At the gun end of the cable 1 there is a handle 45 demountably securedto the exterior of the end structure of the cable. The handle is formedof suitable material, such as hard or synthetic plastic material, havingsuitable electrical insulating and structural strength properties, thatis clamped onto the end portion of the cable structure by bolts and nuts46. The handle carries a depressable trigger 47 adapted to actuate aswitch 48 connected to conductors 8 and 9. At its free end, the handleportion also carries a movable resilient locking member 49, for apurpose to be later described.

The gun 3 shown in FIGS. 1, 2 and 6 to 12 inclusive is a preferred typeembodying the invention and may be employed in connection with the abovedescribed cable. The gun makes electrically conductive and gastightengagement with one of the connector members 22 of the cable, and feedselectrode wire, electrical current, and shielding gas to the weldingzone. This gun comprises a suitably curved body 51 of electricallyconductive metal such as aluminum, brass or copper, the metal preferablybeing the same as that of which connector member 22 and nut member 28are formed. Preferably member 51 is machined at its ends from anextruded blank of suitable cross section, such as that shown in FIG. 7.One end portion 52 of this member is circular in cross section having adiameter decreasing toward its free end; the outer surface 53 of thisportion, which is preferably frustoconical, is shaped to fit closely ingas-tight electrically conductive relation with the inner wall 39 ofsocket recess 38 in the connector member 22 for substantial andpreferably the major portion of the length of the recess. As shown, endportion 52 also has an annular groove 54 that is generally tapered inthe opposite direction, so that when setscrew 42 is suitably adjustedthe screw end, which is preferably smooth and spheroid, slidably bearsagainst the bottom of groove 54 and holds surface 53 of gun portion 52against surface 39 of socket recess 38 to provide a gas-tight connectionand prevent movement of portion 52 in the socket recess longitudinallyor transversely of the axis of member 22, while permitting rotation ofportion 52 in the socket recess. Mere loosening of setscrew 42 permitsportion 52 to be withdrawn from the socket and the gun to be quicklydisconnected from the cable.

The other end of body member 51 has external threads 55.

While the external cross sectional shape of the gun body 51 may becircular or of other shape, it is preferably generally elliptical asshown in FIG. 7, with the major axis of the ellipse generally parallelto the axis about which the gun body as a whole is curved. Such anexternal shape, together with curvature of the body as a whole, makes iteasier to grasp the gun body during welding, or for removal orreplacement of the gun, preferably, as shown, the member has a largecross sectional area of metal throughout its length, for high electricalconductivity.

Preferably, gun body member 51 has spaced ex truded or machinedlongitudinally extending ribs 56, 57 (FIG. 7) spaced laterally aroundthe body by longitudinally extending grooves 58, 59. Member 51 alsocarries an external flexible sheath 61 preferably formed of siliconerubber or the like, which is heatresistant, electrically insulating, andprovides a good grasping surface. Sheath 61 conforms to the generallyelliptical shape of the gun body and moreover fonns with the grooves 58,59 passages between the sheath and the ribs. The sheath stopssufficiently short of the ends of the gun body to cause the passages tohave open ends. Air may flow by convection through these passages tocool the member 51 and prevent uncomfortably warm temperatures to thehand.

Gun body member 51 has an internal axial through opening 62 thatpreferably (FIGS. 2, 6 and 7) having internal ribs 63 spaced byg'rooves'64 of substantial areas, for passage of shielding gas aroundthe liner. The inner edges of the ribs define an opening sized to fitclosely about a tubular inner liner 65, preferably formed ofheat-and-wear-resistant metal such as stainless steel. Liner 65 has acentral opening 66 throughversely to provide resilient outwardly biasedfingers 68,

the innermost ends of the slots terminating in an unexpanded portion ofthe liner to enable gas to flow from outside the liner to its insidewhen the liner end is in a welding tip. The outer surfaces of theextreme ends of fingers 68 are also tapered inwardly at 69 as shown tofacilitate mounting of a welding tip.

At its outlet end gun member 51 has a generally cylindrical axial recess71, formed by cutting ribs 63 a substantial distance back from the freeend of the member.

A welding tip'72 formed of copper or other metal having desirably highelectrical and heat conductivity, is demountably held in recess 71. Thewelding tip shown in FIGS. 2, 8 and has a larger rear portion 73 ofgenerally cylindrical external shape, and a front generally cylindricalportion 74 of smaller external diameter. The rear portion is sized tofit snugly into recess 71. Tip 72 also has an opening 75 axiallyextending throughout its length, the rear portion 76 of which isenlarged and sized to fit with a press fit over the expanded fingers 68of the liner 65, while the front portion 77 of thetip opening is smallerand is sized to provide a sliding fit with, and good electricalconductivity to, the welding wire E used. Tip 72 also has severaltransverse openings 78 from the inner end of larger opening 76 to theexterior.

The welding tip can 'be readily inserted into recess 71 and be firmlybut demountably held in place (FIG. 2) by the inner wall of the recessand the press fit of the fingers 68 on the interior surface'of the tipopening portion 75, transverse openings 78 being located beyond the endof gun member 51 so they communicate with the tip exterior.

A bushing 80, formed of suitable heat-resistant electrical insulatingmaterial having considerable structural strength such as a thermosetphenolic resin, is threaded by internal threads onto external threads 55on discharge end of the gun member 51. This bushing has at its rear endan enlargement 81 protecting the entrances to the external coolingpassages of the gun, and at its front end is turned inwardly to providea stop 82 to locate the bushing axially. The outer surface of thebushing has a groove carrying a split retainer ring 84 formed of springmetal.

A tubular shield or nozzle 85 formed of suitable material such as copperhaving good heat-resistant and conducting properties, has an internalsize such that it can he slipped onto bushing 80 and held in place bypressure of the retainer ring84 against the sleeve inner wall. Theshield is preferably long enough to extend somewhat beyond the end ofthe weldingtip.

The construction is such that the shield is held firmly in place duringuse, but can be readily slipped off as required merely by an axialmovement, without the nec'essity of unscrewing it or removing lockingscrews or rings or the like. The welding tip similarly is held firmly inplace during use but can be readily removed by merely sliding it onaxially from the press fit that holds it in place. A new welding tip canbe readily inserted, and the shield can be replaced, all within a veryshort time, merely by pushing them back in place.

The locking member 49 on the cable can engage any one of several groovesbetween ribs on the exterior of the body member 51 of the gun to preventit from rotating; however, when the locking member is disengaged fromall grooves by mere pressure of the finger on the resilient lockingmember to move it toward tne end of the cable the gun can be rotatedinto any one of a wide range of anulgar positions relative to the axisof the connector portion 21 and to the cable, after which the lockingmember can be released to engage with the adjacent groove. Thus it ispossible readily and quickly to move the gun to an angular position mostdesired for welding, and readily to secure it there.

The feeder means 4 of the illustrated apparatus, shown in detail inFIGS. 3 and 4, comprises a connector member 22 that is identical withthe member 22 at the other end of the cable and that is connected to thecable assembly made up of inner sheath 13, conductive sheath 14, andouter sheath 16 in the manner identical to that described above, throughuse of an identical nut member 29. A bracket 86 closely fits aroundmember 22 and provides a connection for welding current wire 6. Thebracket is secured by a threaded conduit 87extending through the bracketinto opening 43 of member 22. Gas supply hose 5 is connected to thisconduit, and supplied gas to the inner passage 40 of the member 22.Liner 18 extends into such passage to the end of socket recess 38. Gasthen can pass from the hose 5 to the space between passage 40 and theliner, through space 20 between the liner 18 and inner sheath 13, thenceinto the space in the gun between the liner 65 and opening 62 in gunmember 51 and out through the welding tip as described above into thespace between the tip and shield 85.

An electrode wire feed member 88, shown as inserted into socket 38. ofmember 22, has a tapering surface that fits closely against the innersurface of the socket. This member also has a groove 89 identical withgroove 54 of thegunaA setscrew 90 threaded into opening 41 of member 22may be used to lock member 88 in the socket and if desired, permitrelative rotation between members 22 and 88. Member 88 has an internalliner 91 suitably secured.

A washer 92, preferably or felt or other suitable resilient fibrousmaterial, having a central opening, and if desired another aperturedwasher 93 formed of resilient rubber or the like to exert pressure onwasher 92, are located between the bottom of socket 38 and the bottom ofmember 88. The washers, particularly the felt washer, wipe the wirepassing from member 88 into the liner 18 to clean it of dirt particlesor dust that could cause clogging or undesired abrasion to theapparatus. The washers also prevent gas leakage outwardly through thebottom of socket 38 or along the wire.

The apparatus described has the following advantages, among others.Complete relative rotational movement is permitted between the cable andthe welding gun, and if desired between the cable and the feeder, andthe gun can be easily positively secured in a desired rotationalposition relative to the cable. Both the feeder and the gun are held andprevented from movement longitudinally relative to the cable.

Despite such permitted relative rotation movement, there are completelygas-tight joints and excellent electrical contacts between the feederand the conductive sheath through the cable, and between the conductivesheath and the conductive portions of the gun to the welding tip of thegun. The welding gun can be readily and rapidly disconnected from thecable merely by loosening set screw 42, and pulling longitudinally ofthe cable. Similarly, it can be reconnected by inserting its end in thesocket 38 and suitably adjusting setscrew 42. The feeder member 88 canbe similarly handled.

The extended heat transfer surfaces on the outer and inner surfaces ofthe body member of the gun making possible air cooling along the outerportion of the gun and the gas cooling inside the gun and atthe weldingtip, provide a gun that is comfortable to the touch and more resistantto heat deterioration. In the gun disclosed there cannot be anelectrical short between the shield and the welding tip since allexterior portions of the gun are completely electrically insulated fromthe welding tip and from all other portions of the gun that conductelectricity. Heat from the shield at the welding end of the gun cannotbe conducted back to the rest of the gun as the sleeve is heated becausethe shield is heat-insulated from the remainder of the gun. The onlyportions of the gun that can deteriorate are the welding tip and theshield, both of which can be replaced with ease and at low cost.Therefore, much less of the gun need be replaced than in conventionalguns.

The gun can .be connected to and disconnected from the cable withoutdisassembling the gun or the cable. The connector members of the cablecan be readily assembled to or disassembled from the cable without theneed of welding or cutting or other complicated procedures, and thefeeder portion can be connected or disconnected to the cable withoutdifficulty. If necessary these end portions can be readily removed andreassembled on other cables or on opposite ends of the same cable.

It is apparent that various modifications may be made in theillustrative apparatus without departing from the spirit of theinvention. It is intended that the patent shall cover by suitableexpression in the claims, the features of patentable novelty that residein the invention.

What is claimed is:

1. In a welding gun having a handle portion and a nozzle portionconnected to said handle portion by an elongated metal body having aninlet end connected to said handle portion and an outlet end connectedto said nozzle portion, said handle portion including means to connectsaid handle portion to a source of electrical current and a source ofshielding gas for supplying electrical current and shielding gas to saidnozzle portion through said body, the improvement in said elongated bodycomprising, a first passage extending longitudinally through said body,means for removably connecting the inlet end of said body to the handleportion to conduct electrical current through the body and conductshielding gas form said handle portion through the first passage, meansat the outlet end of said body to discharge gas and means to conductelectrical current to said nozzle portion, means carried by said bodyproviding an outer surface over said body and cooperating therewith toprovide at least one second passage between the surface of said body andthe means providing the outer surface and extending for a major portionof the length of said body, said at least one second passage beingindependent of said first passage and having an inner heat transfersurface defined by and forming part of said body, and means providing afirst opening at the inlet end of said body and a second opening at theoutlet end of said body to define with said at least one second passagea continuous opening to provide cooling of said body and said outersurface by convection air flow through said first and second openingsand said at least one second passage.

2. The gun of claim 1 wherein said at least one second passage comprisesa plurality of said second passages between said body and said meansproviding said outer surface, each of said second passages having saidinner heat transfer surface and communicating with the atmospherethrough said opening spaced longitudinally of said body to permit air topass through each of said second passages from one of said openings tothe other of said openings in contact with said inner heat transfersurface of said passage to cool said body and said means providing saidouter surface.

3. The gun of claim 2 in which said body is formed with external ribsthereon separated by grooves, and in which said means on said bodyproviding said outer surface of said gun is a tubular member mounted onsaid body and contacting the outer edges of said ribs, said grooves andsaid tubular member cooperating to form said second passages, and saidinner heat transfer surfaces comprising the surfaces of said grooves.

4. The gun of claim 1 in which said first passage through said body hasinternal ribs extending laterally and axially of said body in saidpassage, and which gun comprises a tubular liner within the spacedefined by the inner edges of said internal ribs, said liner having alongitudinal opening extending through said liner and providing a thirdpassage through which welding wire may pass in use of said gun, andmeans for passing said shielding gas through said first passage in thespace between said internal ribs and said liner.

5. The gun of claim 1 wherein said nozzle portion comprises a bushingformed of heat resistant electrically non-conductive material fixed tosaid outlet end of said body, a shielding sleeve that is demountablyheld on said bushing, and resilient snap-ring means operating betweensaid bushing and said sleeve to demountably hold said sleeve on saidbushing.

6. A welding gun adapted to be connected to means for supplying gascomprising a rigid elongated body having a passage for gas extendinglongitudinally through the body, said body having at one endconstituting its inlet end means for connecting said body to said meansfor supplying gas so that gas will pass into and through said passage,said body having at its other end constituting its outlet end a recessin which said passage terminates, a tubular liner in said passage havingan end portion of said liner that is spaced from the inner wall of saidrecess of said body and has radially sprung fingers in said liner endportion, and a welding tip in said recess of said body that is held inplace in said space in said passage outside of said liner into theinside of said end portion of said liner and from thence into the insideof said welding tip from which it discharges adjacent said outlet end ofsaid body to permit said gas to act as shielding gas and cooling gas forcooling said welding tip.

1. In a welding gun having a handle portion and a nozzle portionconnected to said handle portion by an elongated metal body having aninlet end connected to said handle portion and an outlet end connectedto said nozzle portion, said handle portion including means to connectsaid handle portion to a source of electrical current and a source ofshielding gas for supplying electrical current and shielding gas to saidnozzle portion through said body, the improvement in said elongated bodycomprising, a first passage extending longitudinally through said body,means for removably connecting the inlet end of said body to the handleportion to conduct electrical current through the body and conductshielding gas from said handle portion through the first passage, meansat the outlet end of said body to discharge gas and means to conductelectrical current to said nozzle portion, means carried by said bodyprOviding an outer surface over said body and cooperating therewith toprovide at least one second passage between the surface of said body andthe means providing the outer surface and extending for a major portionof the length of said body, said at least one second passage beingindependent of said first passage and having an inner heat transfersurface defined by and forming part of said body, and means providing afirst opening at the inlet end of said body and a second opening at theoutlet end of said body to define with said at least one second passagea continuous opening to provide cooling of said body and said outersurface by convection air flow through said first and second openingsand said at least one second passage.
 2. The gun of claim 1 wherein saidat least one second passage comprises a plurality of said secondpassages between said body and said means providing said outer surface,each of said second passages having said inner heat transfer surface andcommunicating with the atmosphere through said opening spacedlongitudinally of said body to permit air to pass through each of saidsecond passages from one of said openings to the other of said openingsin contact with said inner heat transfer surface of said passage to coolsaid body and said means providing said outer surface.
 3. The gun ofclaim 2 in which said body is formed with external ribs thereonseparated by grooves, and in which said means on said body providingsaid outer surface of said gun is a tubular member mounted on said bodyand contacting the outer edges of said ribs, said grooves and saidtubular member cooperating to form said second passages, and said innerheat transfer surfaces comprising the surfaces of said grooves.
 4. Thegun of claim 1 in which said first passage through said body hasinternal ribs extending laterally and axially of said body in saidpassage, and which gun comprises a tubular liner within the spacedefined by the inner edges of said internal ribs, said liner having alongitudinal opening extending through said liner and providing a thirdpassage through which welding wire may pass in use of said gun, andmeans for passing said shielding gas through said first passage in thespace between said internal ribs and said liner.
 5. The gun of claim 1wherein said nozzle portion comprises a bushing formed of heat resistantelectrically non-conductive material fixed to said outlet end of saidbody, a shielding sleeve that is demountably held on said bushing, andresilient snap-ring means operating between said bushing and said sleeveto demountably hold said sleeve on said bushing.
 6. A welding gunadapted to be connected to means for supplying gas comprising a rigidelongated body having a passage for gas extending longitudinally throughthe body, said body having at one end constituting its inlet end meansfor connecting said body to said means for supplying gas so that gaswill pass into and through said passage, said body having at its otherend constituting its outlet end a recess in which said passageterminates, a tubular liner in said passage having an end portion ofsaid liner that is spaced from the inner wall of said recess of saidbody and has radially sprung fingers in said liner end portion, and awelding tip in said recess of said body that is held in place in saidrecess by press-fit of said radially sprung fingers of said lineroutwardly against said welding tip.
 7. The gun of claim 6 in which saidliner and said passage are so cross-sectioned that there is a spacebetween the outside of said liner and the inside of said passage throughwhich gas may pass, and in which said welding tip is tubular and saidliner extends within said welding tip and is apertured to permit gas topass from said space in said passage outside of said liner into theinside of said end portion of said liner and from thence into the insideof said welding tip from which it discharges adjacent said outlet end ofsaid body to permit said gas to act as shielding gAs and cooling gas forcooling said welding tip.